Helleborus plant named ‘COSEH 900’

ABSTRACT

A new and distinct cultivar of  Helleborus  plant named ‘COSEH 900’, characterized by its upright and uniformly mounded plant habit; uniform and freely flowering habit; variegated leaves; long flowering period; single light yellow green-colored flowers; and good garden performance.

Botanical designation: Helleborus argutifolius.

Cultivar denomination: ‘COSEH 900’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct cultivar of Helleborus plant, botanically known as Helleborus argutifolius, and hereinafter referred to by the name ‘COSEH 900’.

The new Helleborus plant is a product of a planned breeding program in Glandorf, Germany. The objective of the breeding program was to create new uniform Helleborus plants with unique and attractive plant habit, leaf and flower coloration and resistance to pests.

The new Helleborus plant originated from a cross-pollination conducted by the Inventor in Glandorf, Germany in February, 2006 of an unnamed proprietary seedling selection of Helleborus argutifolius, not patented, as the female, or seed, parent with an unnamed proprietary seedling selection of Helleborus argutifolius, not patented, as the male, or pollen, parent. The new Helleborus plant was discovered and selected by the Inventor as a single flowering plant from within the progeny of the stated cross-pollination grown in a controlled greenhouse environment in Glandorf, Germany in November, 2007.

Asexual reproduction of the new Helleborus plant by divisions in a controlled greenhouse environment in Glandorf, Germany since February, 2008 has shown that the unique features of this new Helleborus plant are stable and reproduced true to type in successive generations.

SUMMARY OF THE INVENTION

Plants of the new Helleborus have not been observed under all possible environmental conditions and cultural practices. The phenotype may vary somewhat with variations in environmental conditions such as temperature and light intensity without, however, any variance in genotype.

The following traits have been repeatedly observed and are determined to be the unique characteristics of ‘COSEH 900’. These characteristics in combination distinguish ‘COSEH 900’ as a new and distinct Helleborus plant:

-   -   1. Upright and uniformly mounded plant habit.     -   2. Uniform and freely flowering habit.     -   3. Variegated leaves.     -   4. Long flowering period.     -   5. Single light yellow green-colored flowers.     -   6. Good garden performance.

Compared to plants of the parent selections, plants of the new Helleborus are more uniformly mounded and are more uniformly and freely flowering.

Plants of the new Helleborus can be compared to plants of Helleborus argutifolius×Helleborus argutifolius ‘COSEH 700’, disclosed in U.S. Plant Pat. No. 21,003. In side-by-side comparisons conducted in Glandorf, Germany, plants of the new Helleborus differed from plants of ‘COSEH 700’ in leaf and flower color.

BRIEF DESCRIPTION OF THE PHOTOGRAPHS

The accompanying colored photographs illustrate the overall appearance of the new Helleborus plant showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type. Colors in the photographs may differ slightly from the color values cited in the detailed botanical description which accurately describe the colors of the new Helleborus plant.

The photograph on the first sheet comprises a side perspective view of a typical flowering plant of ‘COSEH 900’ grown in a container.

The photograph on the second sheet is a close-up view of a typical flower of ‘COSEH 900’.

DETAILED BOTANICAL DESCRIPTION

The aforementioned photographs and following observations, measurements and values describe plants grown during the winter in 15-cm containers in a glass-covered greenhouse in Glandorf, Germany and under environmental conditions and cultural practices which closely approximate commercial Helleborus production. During the production of the plants, day temperatures ranged from 12° C. to 32° C. and night temperatures ranged from 3° C. to 18° C. Plants were 14 months old when the photographs and the description were taken. In the following description, color references are made to The Royal Horticultural Society Colour Chart, 2007 Edition, except where general terms of ordinary dictionary significance are used.

-   Botanical classification: Helleborus argutifolius ‘COSEH 900’. -   Parentage:     -   -   Female, or seed, parent.—Unnamed proprietary seedling             selection of Helleborus argutifolius, not patented.         -   Male, or pollen, parent.—Unnamed proprietary seedling             selection of Helleborus argutifolius, not patented. -   Propagation:     -   -   Type.—By tissue culture.         -   Time to initiate roots.—About two months at 12° C.         -   Time to produce a rooted young plant.—About six months at             4° C. to 15° C.         -   Root description.—Thick to thin, fleshy; white to brown in             color.         -   Rooting habit.—Sparse. -   Plant description:     -   -   Plant form and growth habit.—Herbaceous perennial; upright             and uniformly mounding plant habit with flowers held just             above the foliar plane; plant shape is globular; moderately             vigorous growth habit.         -   Plant height.—About 27.5 cm.         -   Plant diameter (area of spread).—About 26.3 cm. -   Foliage description:     -   -   Arrangement.—Leaves arranged in a basal rosette; leaves             palmately compound with three leaflets per leaf.         -   Leaf length.—About 11.4 cm.         -   Leaf width.—About 14.9 cm.         -   Leaflet length.—About 9 cm.         -   Leaflet width.—About 5.4 cm.         -   Leaf shape.—Palmate; deltoid to reniform in outline.         -   Leaflet shape.—Broadly ovate to broadly obovate.         -   Leaflet apex.—Acute.         -   Leaflet base.—Attenuate.         -   Leaflet margin.—Sharply serrate.         -   Leaflet texture, upper and lower surfaces.—Smooth, glabrous;             leathery.         -   Leaflet venation pattern.—Pinnate.         -   Leaflet color.—Developing leaves, upper surface: Close to             146A heavily dotted with close to 193B and 193C. Developing             leaves, lower surface: Close to 147C to 147D and 148C to             148D. Fully developed leaves, upper surface: Between N137A             and 147A heavily dotted with close to 193D and 194D;             venation, close to 144A to 144B. Fully developed leaves,             lower surface: Between 147C and 148B; venation, between 144C             and 146C.         -   Petiole.—Length: About 5.8 cm. Diameter: About 6 mm.             Texture, upper and lower surfaces: Smooth, glabrous. Color,             upper and lower surfaces: Close to 145A to 145B slightly             dotted with close to 177B to 177C. -   Flower description:     -   -   Flower shape and habit.—Single rotate flowers arranged in             terminal and axillary cymes; freely and uniform flowering             habit with about 50 flowers and flower buds developing per             plant; flowers facing outwardly to slightly nodding and             slightly upright.         -   Fragrance.—None detected.         -   Natural flowering season.—Plants begin flowering about ten             months after planting; long flowering period, plants flower             from late winter to early spring in Germany.         -   Flower longevity on the plant.—About ten days; flowers not             persistent.         -   Flower buds.—Length: About 1.6 cm. Diameter: About 1 cm.             Shape: Obovate. Color: Close to 145C to 145D.         -   Inflorescence height.—About 22.4 cm.         -   Inflorescence diameter.—About 10.4 cm.         -   Flower diameter.—About 5.1 cm.         -   Flower depth (height).—About 2.4 cm.         -   Petals.—Transformed into nectaries.         -   Sepals.—Quantity and arrangement: Five arranged in a single             whorl. Length: About 2.4 cm. Width: About 2.2 cm. Shape:             Broadly elliptic to broadly obovate. Apex: Obtuse. Margin:             Entire. Texture, upper and lower surfaces: Smooth, glabrous.             Color: When opening, upper surface: Close to 145D tinged             with close to 145B. When opening, lower surface: Close to             145C. Fully opened, upper surface: Close to 150D heavily             tinged with close to 145B to 145C; with development, color             becoming closer to 145B to 145B tinged with close to 138B to             138C. Fully opened, lower surface: Close to 145C to 145D.         -   Peduncles.—Strength: Moderately strong. Length: About             15.6 cm. Diameter: About 6 mm. Aspect: About 10° from             vertical. Texture: Smooth, glabrous. Color: Close to 157C to             157D.         -   Pedicels.—Strength: Moderately strong. Length: About 3.4 cm.             Diameter: About 2 mm. Aspect: Erect to about 20° from the             peduncle axis. Texture: Smooth, glabrous. Color: Close to             157A to 157B.         -   Reproductive organs.—Stamens: Quantity per flower: About 80.             Filament length: About 1.6 cm. Filament color: Close to             157D. Anther shape: Reniform. Anther length: About 1.5 mm.             Anther color: Close to 150C. Pollen amount: Scarce. Pollen             color: Close to 158D. Pistils: Quantity per flower: About             five. Pistil length: About 1.2 cm. Stigma shape:             Club-shaped. Stigma color: Close to 150D. Style length:             About 1.1 cm. Style color: Close to 145C to 145D. Ovary             color: Close to 145D. Nectaries (transformed petals):             Quantity per flower: About twelve. Length: About 8 mm.             Diameter, apex: About 2 mm. Diameter, base: About 1 mm.             Shape: Flattened triangular. Color: Close to 144C; towards             the base, close to 144A.         -   Seeds and fruits.—Seed and fruit development have not been             observed on plants of the new Helleborus. -   Garden performance: Plants of the new Helleborus have been observed     to have good garden performance and to tolerate rain and wind;     plants of the new Helleborus have been observed to tolerate high     temperatures of about 35° C. and are hardy to USDA Hardiness Zone 5. -   Pathogen & pest resistance: Plants of the new Helleborus have not     been observed to be resistant to pathogens and pests common to     Helleborus plants. 

It is claimed:
 1. A new and distinct Helleborus plant named ‘COSEH 900’ as illustrated and described. 